A great introduction has three components: a great hook or attention-getting statement to hook the reader into reading it, background or context in which you are writing and always including the author and title, and the last part, though not necessarily always last is the thesis.

These components are generally inorder so a very short paragrpah could have three sentences in which the components are in order.

A great thesis statement would always have your opinion and controlling ideas as to why or what makes it so, such as: Curly's wife feels isolated and lonely (opinion) because her husband is never around (controlling idea #1), he never satisfies her emotionally (#2), and she feels that life is passing her by (#3).

You might like to try and take a slightly different angle by focussing on something a bit more attention-grabbing. When I read this novel what strikes me is how my emotions are torn between equal sympathy and loathing for Curly's wife. A statement to begin your introduction might be as follows:

Arguably, the most divisive character in Of Mice and Men is Curly's wife.

This is the kind of "hook" that would draw a reader in and encourage them to read on. Good luck!

There have been criticisms which suggest that Curley's wife, the only woman in the novella, is an Eve in Of Mice and Men. For, she is a temptress, certainly, but she also undermines the fraternity of men (an important theme of Steinbeck's) and is a direct cause of their futher aggressive and alienation from one another.

(You may wish to find some literary criticisms with this topic to use as documentation before writing your own paper.)

You could argue that Curley's wife brings it all on herself. There is evidence to support that, in her actions and words. For example, a unique thesis statement would be: In Of Mice and Men, Steinbeck explores the theme that we create our own isolation.